Estimation of the Flux of Inorganic Nitrogen and Analysis of Eutrophic Symptoms in Qinzhou Bay

The flux of inorganic nitrogen flowing into Qinzhou Bay was estimated based on the flux of inorganic nitrogen from river into sea,land-based pollution sources directly discharged into sea and aquaculture wastewater. Result showed that the flux of inorganic nitrogen flowing into the Bay was about 7 655 t in 2011,among which the flux of inorganic nitrogen from river accounted for 96.4% of the total flux,and followed by the flux of inorganic nitrogen from land-based pollution sources directly discharged into sea. Inorganic nitrogen from land source accounted for 36.7% share of inorganic nitrogen in the Bay,indicating the anthropogenic impact in the Bay was moderate. Analysis of chlorophyll a indicated that the eutrophic symptoms in the Bay were not obvious,and the eutrophication degree was low. There was some mistake to evaluate eutrophication depending on nutrients only, and it should be combined with eutrophication symptoms to evaluate eutrophication in the offshore.